More than 40 countries have grounded the aircraft, the U.S. was one of the last holdouts.

"The U.S. usually leads the way in safety requirements. I think in this case we lag behind a little bit," said Joe Schwieterman, a DePaul University transportation professor.

And Southwest isn't the only airline. American and United also fly the Max 8, all juggling schedules on the brink of Spring Break.

"I realize this disruption will inconvenience our customers during a very busy Spring travel season. We will do everything in our power to mitigate the operations," said Southwest CEO Gary Kelly in a video statement released by the airline.

Officially, the FAA acting administrator said a software update of the plane is coming soon.

"The software fix is almost complete and we expect by the end of this month all the testing will be complete," said Daniel Elwell, FAA's acting administrator. "We can authorize implementation of the fix by hopefully the end of the month."

But travelers, like Nick Graczyk, remain concerned.

"After it's been up and flying with no issues, I have no issues getting on the plane," he said. "But for right now, I wouldn't want to be the first couple that take off."